Enzymic material and method of preparing same



United States Patent 3,304,238 ENZYMIC MATERIAL AND METHOD OF PREPARING SAME Louis Laufer and Sidney Gutcho, Bronx, N.Y., assignors to Schwarz Bio Research, Inc., Orangeburg, N.Y.

No Drawing. Original application Oct. 3, 1963, Ser. No. 313,433. Divided and this application Oct. 4, 1965, Ser. No. 492,875

10 Claims. (Cl. 19552) This invention relates to the enzyme digestion of nucleic acids and is a division of our copending application Serial No. 313,433, filed October 3, 1963. More particularly the invention relates to enzymic materials capable of digesting ribonucleic acid and the use of such materials for hydrolyzing such acid under specific, controlled conditions in order to obtain specific hydrolysis products termed 5'- ribonucleotides.

Within the context of the present invention the term RNA should be understood to mean ribonucleic acid. The term RNA derivatives refers to ribonucleosides and ribonucleotides as well as compounds which are deriva tives or homologues of these sub-units of RNA. A ribonucleoside is an N-glycoside of a heterocyclic base, generally a pyrimidine or purine. A ribonucleotide is a phosphoric acid ester of a ribonucleoside and may be ribonucleoside monophosphate or a ribonucleoside polyphoshate.

p RNA is a polymeric molecule which occurs widely in nature-often in long chains ranging in molecular weight up to to 10 It is presently thought that RNA polymers (found primarily in the cytoplasmic portions of cells), in various degrees of polymerization, are connected with the synthesis of specific proteins required by the cells. Monomeric nucleotides of RNA are found within cells in combination especially with many of the B vitamins, in which form they function as coenzymes promoting specific reactions necessary for the normal function of the organism.

The polymeric structure of ribonucleic acid and the relation of the polymer to the various possible degradation products may be represented schematically in the following diagram:

R R R R R where: R may be a purine or pyrimidine base, most commonly in nature; adenine, guanine, uracil, or cytosine. The vertical heavy line represents a five-carbon sugar in pyranose configuration (d-ribose) and the numbers 3 and 5 represent respectively the third and fifth carbon of this sugar. P is a phosphate ester bridge connecting adjacent monomers through a linkage between the 3 and 5' carbons.

The polymer schematically shown may be degraded in many ways by a variety of enzymes which have been isolated from mammalian tissue, snake venom, and other living cells such as micro-organisms, at an extremely high cost. The procedure is thought to be usually stepwise with certain alternative pathways. In the illustration above, the enzyme with activity responsible for reducing the size of N (shortening the chain length) is called a nuclease or depolymerase. Once this shortening is acice complished the phosphate bridges can be attacked specifically either at points indicated by the dotted lines, or at the wavy lines. In the former case monomeric units with phosphate esters attached to the 5' position (5-nucleotides) are the sole product whereas in the latter the products are 3'-nucleotides. The name most commonly given to the enzyme having this type of enzymic activity is phosphodiesterase. There is a specific enzyme for each point of attack. Nucleotides may be subsequently further degraded by the splitting oil? of phosphate (by 3' or 5' phosphomonoesterases) and by further cleavage of the base (R) from the sugar. Enzymes which catalyze such hydrolysis are called nucleosidases. Finally, there is also enzyme activity in some cellular extracts which remove NH radicals from bases which contain them. Such enzymes are referred to as deaminases.

Many of the degradation products outlined above have become significant articles of commerce because of their importance in research studies on the chemistry and properties of RNA. .They are also used in pharmaceutical preparations. Also, the 5-ribonucleotides (particularly inosine 5-monoph0sphate (IMP) and guanosine 5-monophosphate (GMP)) have become important as food flavoring enhancers.

It is an object of the present invention to provide a simple, economical, and expeditious method for preparing enzymic materials which are capable of hydrolyzing RNA.

It is another object of the present invention to provide a method for preparing stable enzymic materials which are capable of hydrolyzing RNA to produce high yields of ribonucleotides.

It is a further object of the invention to provide a simple, economical, and expeditious process for producing high yields of nucleotides from RNA using stable enzyme materials which are capable of hydrolyzing RNA to produce such nucleotides.

The above and other objects and features of the invention will appear more fully from the following description.

In accordance with the invention, it has been discovered that the rapidly proliferating parts (the rootlets and stems) of germinating seeds surprisingly constitute a particularly rich source of enzymes which are capable of readily splitting RNA. vIt has also been discovered that such enzymes may be simply and efliciently utilized for such splitting of RNA, particularly for the production of 5-nucleotides.

The proliferating rootlets of the seeds are the richest source of enzymic material, the stems containing less, but useful quantities, whereas the seed or kernel itself does not contain a commercially attractive quantity. The property of the proliferating parts of the seed as a rich source of enzymic material is general property of seeds as a class and is particularly true of monocotyledon seeds. Preferable seeds are: those capable of being malted, such as oats, barley, wheat, corn, rye, mullet, sorghums, and

rice; many varieties of grasses; sunflower; peas; and beans. I

As certain seeds, such as barley (but also to a lesser extent Wheat and rice), are commonly germinated in large quantities commercially, for the production of malt from which the rootlets are generally available as a by-product at low cost, the same are preferable for use in accordance with the invention and render the invention particularly interesting and valuable from a commercial standpoint.

Similarly, in some countries, bean seeds are germinated for the production of bean sprouts, making available a cheap and plentiful supply of these rootlets for the practice of the invention.

We have found that there is little or no loss of enzyme activity if the rootlets or stems are dried, even if such drying is at relatively high temperatures as is generally employed in kilning malt. Furthermore, this activity is retained in the rootlets for a number of years Without any special precautions. 7

As mentioned, economic considerations and ready availability favor dried rootlets of barley malt (commercially known as malt sprouts) as the preferred material. However, any readily available seed rootlet or sprout can be substituted, such as, for example, those from wheat malt, rice malt, or rye malt, or bean shoots, or any of those mentioned above.

In accordance with the present invention the uncomminuted rapidly proliferating parts of germinating seeds are initially treated to obtain an enzymic medium which is capable of hydrolyzing RNA to provide the desired high yields of nucleotides. The seed-parts, which are normally dry, are first either: soaked in water and then washed with a further quantity of water; or subjected to a multiplicity of washings with water. Where the initial treatment of seed-parts comprises soaking followed by washing, the soaking period should extend for from about 30 to 90 minutes to precondition and hydrate the seedparts. The soaked seed-parts are thereafter washed with water to remove bacteria. The washing treatment is particularly important where the seed-parts comprise malted rootlets since such rootlets contain bacteria (resulting from the malting process) which, if not removed, proliterate enzymes destructive to 5-nucleotides. The washing may be continuous with the waste water continuously removed or may be accomplished as a series of batch washings with the waste water removed after each wash period. The water utilized for soaking the seed-parts and/or washing the seed-parts should not be extremely hard, i.e., contain more than about 1000 parts per million of hardness. Where the natural sources of water yield only hard water, the final washing of seed-parts should be preferably carried out using deionized or soft" water.

As mentioned above, the soaking stage may be eliminated provided the washing period is sufficient to accomplish the desired hydration and preconditioning action. Also, to aid in the removal or destruction of harmful bacteria, small quantities of a suitable bactericide may be added to the wash water utilized during one or more of thewashings.

After suflicient washing, additional water is mixed with the washed seed-parts in a preferred ratio of about 5 to 15 parts by weight of water to one part by weight of solids (seed-parts). Where the seed-parts comprise malt sprouts, the ratio of water to solids may be preferably about to 1. a

The water/seed-part suspension or slurry is next sub jected to a relatively short heat treatment (about 0.5 to about 7 minutes and preferably 2 to 5 minutes) during which such suspension is agitated. To effect such treatment, steam may be directly introduced into the suspension in sufficient amount and for a sufficient time to rapidly establish and maintain the temperature of the suspension at between 70 to 85 C. and preferably 70 to 75 C. with optimum commercial results being achieved at about 72 C. Prior to the heating period, and while maintaining agitation of the suspension, phosphatase deactivators or inhibitors are added to the solution. Such deactivators may comprise: metallic ions (zinc), preferably ZnAc -H O, as a deactivator of 5-ribonucleotidase; and borate ions (such as H BO which may act as a deactivator of general phosphatases. During the heat treatment stage it is believed that the particular temperature and enzyme deactivator conditioning of the water/ seed-part suspension results in destruction of phosphatase and monoesterase enzymes and other enzymes with the exception of ribonuclease and phosphodiesterase enzymes which are essential in the subsequent hydrolysis of RNA to 5'-ribonucleotides. For optimum commercial results the heating period is continued after the preferred 70 to C. temperature is reached for a period of about 5 minutes with agitation of the heated suspension continuing for the entire period.

Enzymic media, prepared as described heretofore, have a broad spectrum of activity with respect to ribonucleic acid but, in accordance with the further embodiments of this invention, it has been discovered that by careful control of such activity a surprisingly high yield of 5'- nucleotides may be obtained by hydrolyzing such acid with such media in a relatively short time period. Thus, in accordance with the invention 5'-nucleotides may be selectively obtained from RNA by the reaction of a digestion solution of RNA and enzyme material heated to from about 60 to 70 C. for from about 1% to about 5 /2 hours. The initial pH of the RNA solution may be as high as 8.5 and preferably the pH of the digestion solution does not decrease during hydrolysis to below about 5.2.

It is important that the seed-parts remain substantially in particulate form during the heat treatment stage and during the subsequent RNA hydrolysis stage. Many unexpected and surprising advantages are realized during the RNA hydrolysis by utilization of a heat treated enzyme medium comprised of water and the rapidly proliferating parts of germinating seeds wherein the seed-parts are not comminuted and remain as particulate matter in the medium. Improved enzymic medium to RNA solution ratios are possible. Radically shorter hydrolysis times are required. Significantly simplified solids separation procedures are required and there are less non-enzymatic impurities extracted into the hydrolyzate mixture. In general overall processing of the enzymic medium and hydrolyzate mixture is possible together with the attainment of exceptionally high yields of 5'-mononucleotides in the final hydrolyzed solution.

In accordance with the invention, a ribonucleic acid solution is introduced to a hydrolysis stage together with the enzymic medium (includes seed-parts) from the heat treating stage to form a digestion or hydrolysis solution including suspended seed-parts. The nucleic acid solution, for example, may comprise RNA, water, and appropriate amount of an alkaline material for adjusting the pH of such solution to the preferred alkaline range. Any of the well-known alkaline pH adjusting materials may be used such as: ammonium hydroxide and ammonium carbonate; sodium hydroxide; tris (hydroxy methyl) amino methane; and primary, secondary and tertiary amines which are water miscible.

It has furthermore been found that the presence of zinc ions in the digestion or hydrolysis solution (added to the enzymic medium and carried over to the digestion solution) accelerate the enzyme activity and that a concentration of zinc ions of between about 0-.001M to 0.01M in the digestion solution increases the rate of hydrolysis. Addition of other ions such as calcium, copper, nickel, or iron, however, appears to inhibit the nucleic acid hydrolysis when using enzymic material obtained from malt sprouts as discussed above.

Using an enzymic medium (including seed-parts) as disclosed above and an aqueous RNA solution having an RNA concentration of up to 440%, the digestion or hydrolysis solution (enzymic medium including seedparts-l-RNA solution including pH adjustment agent) a may comprise about 24% RNA with the ratio of enzymic medium to RNA solution being from about 1:1 to about 3:1. .The final digest solution, which may have its pH range adjusted periodically (if necessary) to maintain the same within the range of 5.2 to 8.5, is heated to from about 60 to about 70 C. (preferably 63 to 67 tides.

scribed hereinafter.

The following examples and experiments are given to illustrate the present invention and are not to be construed as limiting.

C.) for from about 1 /2 hours to about 5 /2 hours to obtain maximum conversion of the RNA to 5'-ribonucleo- EXAMPLE 1 A. Preparation of seed-parts.66.6 kg. of dried malt sprout rootlets (Hannchen from National Malt Co.) were suspended in 800 liters of water and agitated for The supernatant liquid was drawn out of the bottom of the wash-mix tank and discarded. Fresh 20 minutes.

activity.

water with 210 g. of ZnAc -H O and 666 g. of H 130; added to the mixture to selectively suppress enzyme The water/seed-part mixture was then rapidly heated with direct steam, while agitating, to 72 C. with the temperature of the mixture maintained at between 71.3 C. and 72.3 C. for 5 minutes.

C. Hydrolysis of RNA .--150 liters of RNA solution (30 kg. of commercial RNA and 500 g. NaF) at pH 7.0-7.1 (adjusted with NaOH) and at 20 C. was added rapidly to the above pretreated water/seed-part suspension with the total mixture agitated and the temperature adjusted to about 65 C. Agitation was continued and the temperature maintained at between 64.5" C. and 65.5 C. for 2 hours. Analysis of the hydrolysis solution indicated nucleic :acid degradation to be 95% with 90% 5'-nucleotides present. The hydrolysis was stopped by lowering the temperature of the mixture to 35 C. and adjustiiig the pH to 3.43.6 by the addition of HCl. was filtered to remove the spent plant parts with the filtrate further treated to obtain the desired 5'-nucleotides free of impurities.

The following tables set forth additional examples to further illustrate the invention.

TABLE I.-SEED-PART PRETREATMENT The digest solution Vol. of Total Vol. Pretreat- Pretreat- Example gleedillzalrifl gfi vgi ggg S Waasfhedt Pretirhezait- $511111: Tment erg g. i ee ar 5 men xe emp mars Each liters ture, liters min. C

*Seed-Parts-Hannchen dried malt sprouts from National Malt Company.

TABLE II.RNA HYDROLYSIS RNA Solu- RNA Solu- Final RNA Final Free Final 5-Nu- Example RNA Wt., tion Vol., tion Temp. RNA Solu- Hydrolysis Hydrolysis Degrada- Pl10S., Percleotides,

kg. liters at Adrition, tiou, pH Time, hrs. Temp., tion, lzercent Percent cen water in the amount of 830 liters was introduced into the wash-mix tank and the mixture agitated for an additional 20 minutes with the wash liquid again drawn out of the tank and discarded. Three additional washings of similar duration were made using substantially equivalent amounts of water.

B. Pretreatment of seed-parts.After the fifth washing the clean wet sprouts were mixed with 830 liters of fresh Examples 8 sprouts from National Malt Co.) are soaked in water for TABLE III.SEEDPART PRETREATMENT varying time periods and thereafter washed once for minutes.

SeedPart Soak Water Soaking Time, Wash Water Vol. Washed Total Vol. Pre- Pretreatment Pretreatment Example Weight, kg. V01., liters min. Vol., liters Seed-Parts, treatment Mix- Time, min. Temp., 0

liters ture, liters TABLE IV.R.NA HYDROLYSIS RNA Solu- RNA Solu- Final RNA Final Free Final 5'-Nu- Example RNA Wt, tion Vol., tion Temp., RNA Solu- Hydrolysis Hydrolysis Degrada- Phos., Pereleotides, kg. liters 0. tion, pH Time, hrs. Temp, 0. tion, lien cent Percent can EXAMPLE Analysis of the experiments set forth in Table V reveals A series of experiments was carried out to determine optimum processing conditions and parameters of operating conditions for producing 5'-mononuc1eotides in accordance with the invention. Experiments (al through (0 set forth in table form below,.relate to processing wherein uifiform lots of dried seed-parts (Hannchen dried malt sprouts from National Malt Co.) were: 1) subjected to five washings each with Water; (2) mixed with water in a ratio of 1.0 kg. of sprouts to 10.9 liters of water; and (3) heat treated as indicated in the table. The resulting enzyrnic medium (including the malt sprouts) in each instance was then: (1) mixed with a 9.0% RNA solution (initial pH of about 7.0) in a ratio of 2.2 kg. of dried sprouts to 1.0 kg. of commercial RNA (about 90% (2) hydrolyzed at about 65 C. for periods of time as indicated. The hydrolysis mixture (as a result of the above proportions) contained 3% RNA. The hydrolyzate (after stopping the enzyme action) was analyzed (as indicated in the table) to determine the resulting percent of nucleotides.

that optimum hydrolysis to form 5'-nucleotides occurs when the heat treatment of the enzymic medium is carried out for about 5 minutes at 70 to 75 C. and the hydrolysis is effected at pH 7.0 (initial pH of the RNA solution) and 65 C. and is run for 2 to 2 /2 hours.

EXAMPLE 11 A further series of experiments was carried out to determine additional processing conditions. Experiments (p throungh set forth in table on next page, relate to processing wherein uniform lots of dried seed-parts (same malt sprouts and quantities as in Example 10) were: (1) subject to five washings each with water; (2) mixed with water in a ratio of 1.0 kg. of sprouts to 10.0 liters of water; and (3) heat treated as indicated in the table. The resulting enzyrnic medium (including malt sprouts) in each instance was then: (1) mixed with a 9.0% RNA solution in a ratio of 2.2 kg. of dried sprouts to 1.0 kg. of commercial RNA (about 90%); and (2) hydrolyzed under varying temperatures and RNA solu- TABLE V Heat Treatment Hydrolyzate Analysis Experi- Hydrolysis,

ment Time, hours RNA Free Phos, 5-Nueleotides,

Temp, C. Time, min. Degradation, percent percent percent 65 5 1% 83. 6 36. 2 47. 4 65 5 2 92. 4 43. 4 49. 0 65 5 2% 95. 9 48. 6 47. 3 65 10 1% 86. 4 25. 8 60. 6 65 1O 2 91. 2 30. 7 60. 5 65 10 2% 96. 1 35.8 60. 3 65 2O 1% 88. 7 16. 0 72. 7 65 20 2 94. 5 19. 5 75. 0 65 20 2% 95. 1 22. 4 72.7 65 1% 87. 8 6. 5 81. 3 40 2 91. 4 7. 5 83. 9 65 40 2% 95. 4 8. 3 87. 1 65 40 5 97. 7 11. 0 86. 7 5 1% 88. 8 5. 2 83. 5 70 5 2 93. 5 6. 2 87. 3 70 5 2% 96. 6 6. 7 89. 9 70 5 5 96. 5 9. 5 87. (l 70 10 1% 88.1 3. 6 84. 5 70 10 2 91. 1 4. 1 S7. 0 70 10 2% 93. O 4. 5 88. 5 7O 20 1% 86. 2 4. 4 81. 8 70 20 2 89. 6 4. 4 85. 2 70 20 2% 92. 4 5. 0 87.4 72 3 1% 88. 8 4. 9 83. 9 72 3 2 91. 0 6. 6 84. 4 72 3 2% 93. 7 6. 3 87. 4 72 5 1% 87. 4 4. 4 33. 0 72 5 2 91. 3 5. 4 85. 9 72 5 3 94. 8 6. 1 88. 7 72 5 4 94. 4 6. 9 87. 5 72 10 1% 85.8 3.9 81.9 72 10 V 2 90. 9 4. 5 86. 4 72 10 2% 90. 3 4. 7 85. 6 72 20 1% 84. 1 3. 7 S0. 4 72 20 2 89. 3 4. 1 95. 2 72 2O 2% 90. 9 4. 4 86. 5 75 3 1% 84. 4 4. 2 80. 2 75 3 2 88. 7 3. 9 S4. 8 75 3 2% 92. l. 4. 2 87. 9 75 5 1% 89. 5 3. 7 S6. 5 75 5 2 92. 2 3. 3 88. 9 75 5 2% 91. 9 3. 7 88. 2 75 5 5 94. 4 5. 7 88. 7 75 10 1% 86.1 2. 7 as. 4 75 10 2 90. 3 3. 1 87. 2 75 10 2% 91. 8 3. 3 88. 5 75 20 1% 83. 9 2. 7 81. 2 75 2O 2 89. 9 3. 2 86. 7 75 20 2% 91. 3 3. 4 87. 9

5-Nucleotides, percent Free Phos., percent 1'0 EXAMPLE 13 Hydrolyzate Analysis wm 4384 63599275995243840.102998014384357 .msmriazz.

om Mamie wnmmmnmm mmmmnw mmmmwsss ssss Time, hours O00000000000000000000005550000000000 7 7 ZZ"A"AZZTZ1ZTamnmfiwTZZZoaemomRwomomTZZZ777777 Time, min.

Heat Treatment Temp, O.

(as indicated in the table) to determine the resulting percent of nucleotides.

Experiment tion pH conditions as set forth below and for periods of time as indicated. The hydrolysis mixture (as a result of the above proportions) contained 3% RNA. The hydrolyzate (after stopping the enzyme action) was analyzed The C. The re- One part -Nucleotides, percent A portion of malt sprouts was washed five times with water and thereafter mixed with water-and heat treated at 72 C. for five minutes with the addition of zinc ion to the mixture at the initiation of the heat treatment. sprouts were separated 'by filtration and mixed wih RNA solution at pH 7.0. The final RNA concentration of the mixture was 3%. NaF was added so that the final solution contained 0.001 M Zn and 0.05% NaF. The solution was heated to, and maintained at, 65 sults of the analysis of the hydrolyzate appear in Table VIII.

A portion of whole malt grains was washed five times Free Phos.,

percent soy bean sprouts, and the rootlets of oats, wheat and rice. with water and separated into two equal parts.

Hydrolyzate Analysis RNA Degraded, percent TABLE VII Hydrolysis, Time, hours EXAMPLE 12 Experiments were carried out to determine the effectiveness of enzymic media formed with the rapidly proliferat- Table VII below, reveals the hydrolysis results of uniform processing in accordance Plant Parts (in 3 do. 4- Soy Bean Sprouts 5- o Oat Rootlets 9 Wheat Rootlets 10- do- -r 1l do 12 Rice R0ot1ets Analysis of the experiments set forth in Table VI reveals that optimum practical hydrolysis to form 5-nucleo- Experiment tides occurs when the heat treatment of the enzymic medium is carried out for about 5 minutes at about 72 and the hydrolysis is effected at pH 6.0 to 8. 5, to C. for 2 to 3 hours.

ing parts of other seeds.

with the invention for like quantities of mung bean sprouts,

; Mung Bean Sprouts 1 1 was ground in a Waring Blendor. Both parts were mixed with equal proportions of water with zinc ion added and heat treated at 72 C. for five minutes. The quantities of water and seed-parts were the same as used during the foregoing experiments involving malt sprouts. Both enzymic media (ground grain and unground grains) were mixed with RNA solution at pH 7.0. The final RNA concentration of both mixtures was 3%. NaF was added 2. The aqueous enzymic medium claimed in claim 1 in which the rapidly proliferating seed-parts are derived from seeds selected from the group consisting of oats, barley, Wheat, corn, rye, rice, grass, bean, pea, melon, papaya, locust bean, sunflower and sesame seeds.

3. The aqueous enzymic medium claimed in claim 1 in which the rapidly proliferating seed parts are substantially seed-free malted barley rootlets.

4. The aqueous enzymic medium claimed in claim 1 as g Each Solution was and maintained in which the'ratio of seed-parts to water is about 1 part at, 65 C. The results of the analysis of the hydrolyzate b weight of seed-parts to about 5 to about parts by appear in Table VIII. weight of water.

TABLE VIII Hydrolyzate Analysis Time of Enzymic Media Hydrolysis,

Hours RNA De- Free Phos., 5'-Nucle0tides,

graded, percent percent percent Filtered Sprouts- 1% 96. 2 8. 9 87, 3 Do 2 100.0 9.8 91.2 Ground Malt Grain 1% 50.0 9.5 40. 5 Do 2 46.0 11.0 35.0 Do 3 51. 6 13. U 38. 6 Whole Malt Grain. 1% 9. 4 3.8 4. 6 g 11. 3 4. 3 7. 0

After hydrolysis of the RNA to 5-nucleotides, impurities which may hamper subsequent separation of the 5'- nucleotides are removed. Such impurities are mainly (I) inorganic phosphates, (2) protein from the enzymic medium, (3) small amounts of unhydrolyzed nucleic acid, and (4) nucleosides. The first three can be removed by at least two methods. One method involves the addition of barium hydroxide to pH of 9.0. The barium hydroxide addition stops enzyme action immediately and causes precipitation of impurities which can be removed from the 5'-nucleotide solution by filtration. This method may result in the removal of small amounts of the desired 5'-nucleotides, particularly purine nucleotides.

A second method of removing impurities involves the addition to the hydrolysis solution of alcohol to stop enzyme action and precipitate protein and some sodium phosphate. Small amounts of purine nucleotides are also precipitated. The precipitate is filtered off and the filtrate used to separate 5-nuc1eotides.

Whichever of the above methods for purifying the hydrolyzate is used, the filtrate (after removal of impuri ties) contains nucleotides which may be separated by well-known ion-exchange techniques.

It should be understood that an enzymic media comprised of water and uncomminuted seed-parts (which has been heat treated in a manner similar to that described herein before) may be utilized to degrade or digest deoxyribonucleic acid to form 5'-deoxyribonucleotides.

While the foregoing specification sets forth preferred embodiments of the invention, it is to be understood that the invention is not limited to the exact details shown and described, and that variations and modifications may be made in conventional manner without departing from the scope of the invention as defined in the appended claims.

We claim: a

1. An aqueous enzymic medium capable of digesting ribonucleic acid to form primarily 5'-ribonucleotides comprising a dispersion of discrete rapidly proliferating substantially non-comminuted seed-parts selected from the group consisting of substantially seed-free germinating seed rootlets and substantially seed-free germinating seed stems in water, said mixture having been heated to from between about 70 to about 85 C..for from about 0.5 to about 7 minutes.

5. The aqueous enzymic medium claimed in claim 1 in which the mixture of seed-parts and water undergoes heating in the presence of zinc ions.

6. A method for the preparation of an aqueous enzymic medium capable of digesting ribonucleic acid to form primarily 5-ribonucleotides which comprises:

mixing a quantity of discrete rapidly proliferating substantially non-comminuted seed-parts selected from the group consisting of substantially seed-free germinating seed rootlets and substantially seed-free germinating seed stems with water in a weight ratio of seed-parts to water of from about 1 to 5 to about 1 to 15; and

heating the mixture of substantially non-comminuted seed-parts and water at a temperature of between about 70 to about C. for from about 0.5 to about 7 minutes to form an aqueous dispersion of said seed-parts which is rich in phosphodiesterase enzymes and substantially free of phosphatase and monoesterase enzymes.

7. The method for the preparation of an aqueous enzymic medium capable of digesting ribonucleic acid to form primarily 5'-ribonucleotides as claimed in claim 6 in which the rapidly proliferating seed-parts are derived from seeds selected from the group consisting of oats, barley, wheat, corn, rye, rice, grass, bean, pea, melon, papaya, locust bean, sunflower and sesame seeds.

8. The method for the preparation of an aqueous enzymic medium capable of digesting ribonucleic acid to form primarily 5'-ribonucleotides as claimed in claim 6 in which the rapidly proliferating seed-parts are substantially seed-free malted barley rootlets.

9. The method for the preparation of an aqueous enzymic medium capable of digesting ribonucleic acid to form primarily 5'-ribonucleotides as claimed in claim 6 in which the mixture of seed-parts and water is heated at a temperature of between about 70 to about 75 C. for from about 2 to about 5 minutes.

10. The method for the preparation of an aqueous enzymic medium capable of digesting ribonucleic acid to form primarily 5'-ribonucleotides as claimed in claim 6 in which zinc ions are added to the mixture of seedparts and water during heating thereof.

(References on following page) 13 14 References Cited by the Examiner Schlamowitz et al.: J. Biol. Chem., vol. 163, pages UNITED STATES PATENTS 487 to 1946- Shuster: Journal of Biological Chemistry, vol. 229, 3,120,511 2/1904 Tanaka et al. 19528 pages 28910 November-December 19 3,163,586 12/1964 I hida et a1, 195 28 5 Shuster et al.: J. Biol. Chem, vol. 201, pages 535 to 3,168,446 2/1965 Omura et al. 195-28 546, 1953- OTHER REFERENCES A. LOUIS MONACELL, Primary Examiner.

Kuninaka et al.: Agr. Biol. Chem, vol. 25, No. 9, p g 693 to 1961. ALVIN E. TANENHOLTZ, Examiner. 

1. AN AQUEOUS ENZYMIC MEDIUM CAPABLE OF DIGESTING RIBONUCLEIC ACID TO FORM PRIMARILY 5''-RIBONUCLEOTIDES COMPRISING A DISPERSION OF DISCRETE RAPIDLY PROLIFERATING SUBSTANTIALLY NON-COMMINUTED SEED-PARTS SELECTD FROM THE GROUP CONSISTING OF SUBSTANTIALLY SEED-FREE GERMINATING SEED ROOTLETS AND SUBSTANTIALLY SEED-FREE GERMINATING SEED STEMS IN WATER, SAID MIXTURE HAVING BEEN HEATED TO FROM BETWEEN ABOUT 70 TO ABOUT 85* C. FROM ABOUT 0.5 TO ABOUT 7 MINUTES. 